High-enthalpy fluid injection integrated with glow plug

ABSTRACT

Disclosed is a turbocharged internal combustion piston engine system that includes a waste-heat recovery system. The waste-heat recovery system involves injecting heated water into the cylinders during combustion to increase engine power and efficiency and to reduce emissions. The engine can be a spark or compression ignition type of engine, and can utilize fuels including but not limited to diesel, natural gas, gasoline, and ethanol. The engine also includes a turbocharger that utilizes a turbine in the exhaust gas flow to provide power to a compressor in the intake air flow to pressurize the intake air and provide additional charge flow to the engine to increase engine output.

BACKGROUND

Waste heat recovery in various types of combustion engines is a way toimprove the overall efficiency of these systems. Waste heat recoverysystems range from power plants that have bottoming cycles, tothermoelectric systems that generate electricity. Power plants that havebottoming cycles utilize the excess heat in the low pressure exhaustgases from the primary work generating cycle. Thermoelectric systemsutilize similar waste heat sources.

On piston engines, waste heat recovery systems can consist of a closedloop Rankine Cycle. A Rankine Cycle uses the heat from the exhaust topower the cycle. These systems typically have a separate, dedicated,expander that extracts power from the working fluid and is connected tothe crankshaft of the engine.

SUMMARY

An embodiment of the invention may therefore comprise a waste heatrecovery system for a turbocharged engine, comprising: an internalcombustion engine with one or more cylinders; a turbocharger thatextracts energy from exhaust gasses of said internal combustion engineand compresses intake air of said internal combustion engine; a pump topressurize a fluid; one or more heat exchangers to heat said fluid usingwaste heat from said internal combustion engine; and, one or moreelectronically controlled direct injectors to inject said fluid that hasbeen pressurized and heated into at least one engine cylinder of saidinternal combustion engine.

An embodiment of the invention may therefore further comprise a methodof recovering waste heat for a turbocharged engine, comprising:providing an internal combustion engine with one or more cylinders;providing a turbocharger that extracts energy from exhaust gasses ofsaid internal combustion engine and compresses intake air of saidinternal combustion engine; pressurizing a fluid to produce pressurizedfluid; heating said pressurized fluid with waste heat from said internalcombustion engine to produce supercritical fluid; and, injecting saidsupercritical fluid into one or more cylinders of said engine such thatthe fluid flashes into a vapor thereby providing power to said one ormore cylinders during a power stroke of said one or more cylinders.

An embodiment of the invention may therefore further comprise aturbocharged engine system, comprising: a turbocharger comprising aturbine and a compressor;

a tank to hold water; a pump to pressurize water from said tank therebyproducing pressurized water; one or more heat exchangers to, using heatproduced by the engine system, heat said pressurized water to asupercritical state thereby producing supercritical water; and, aninjector to inject said supercritical water into a cylinder of theengine system at a timing corresponding to combustion in said cylinder,so that said water provides additional power to said cylinder during apower stroke of said cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration depicting a waste heat recovery system.

FIG. 2 is a plot of a T-s diagram for water illustrating the physicalstates water takes as it is heated and injected into the cylinders.

FIG. 3 illustrates a direct injector that injects both fuel and steaminto the engine cylinders.

FIG. 4 illustrates a direct injector that is integrated into a glowplug.

FIG. 5 illustrates a direct injector that is integrated into a sparkplug.

DETAILED DESCRIPTION OF THE EMBODIMENTS

An embodiment uses the pistons of the engine as the expander for thewaste-heat recovery system, where the working fluid is supercriticalwater or steam that is injected into the cylinders. In this embodiment,a separate mechanical expander is not needed. The system cansimultaneously be used to reduce NOx emissions by acting as a moderatorduring combustion in the cylinders.

In an embodiment, a turbocharged internal combustion piston enginesystem includes a waste-heat recovery system. This system injects heatedwater into the cylinders during combustion to increase engine power andefficiency, and to reduce emissions. The engine can be a spark orcompression ignition type of engine. The engine can utilize fuelsincluding, but not limited to, diesel, natural gas, gasoline, andethanol. The engine can also include a turbocharger that utilizes aturbine in the exhaust gas flow to provide power to a compressor in theintake air flow that pressurizes the intake air and provides additionalcharge flow to the engine to thereby increase engine output.

The waste-heat recovery system comprises a water supply, a high pressurepump, one or more heat exchangers that capture waste heat from theengine, and electronically controlled cylinder direct injectors thatinject the pressurized and heated water into the engine cylinders with atiming that corresponds to the combustion of the fuel in the cylinders.In the case of a stationary engine, such as in a generator set, thewater source may be a filtered water supply. The water source may befrom a tank that is refilled periodically, much like a fuel tank in anon-road vehicle. Since water is a product of combustion. The watersource may be water condensed out of the exhaust gas flow. The watersource may be a combination of two or more of the aforementioned watersources.

In an embodiment, the high pressure water pump can be a positivedisplacement pump driven by the engine. The high pressure pump receiveswater from the water source and pressurizes it to a high pressure. Forexample, the water may be pressurized to a pressure that is in the rangeof 200+ bar. The water is then passed through one or more heatexchangers to heat the water with engine waste heat sources. Examples ofwaste heat sources that can be used to heat the water include: (1) theengine cooling water before it reaches the radiator; (2) exhaust gasafter it has passed through a turbine; (3) exhaust after emissionsafter-treatment that requires high temperatures; (4) an intercooler; (5)an EGR cooler; and any other sources of waste heat.

Once the pressurized water is heated, it can be then distributed to theinjectors in each cylinder through a rail-like bank. This rail-like bankcan be much like in a common rail diesel fuel injection system. Theinjectors receive electrical signals from an engine controller to injectthe high-enthalpy water during the end of the compression stroke and thebeginning of the power stroke. In an embodiment, this is when combustionin the cylinder occurs. When injected, the water flashes into steam whenit reaches the lower pressure of the cylinder. When the water flashesinto steam it expands to help push the piston down during the powerstroke thereby providing additional power to the engine. The injectedwater also acts as a moderator in the cylinder that absorbs heat fromthe combustion. This helps to keep cylinder temperatures lower therebyhelping to reduce NOx emissions as well as reducing heat transfer to thecylinder walls. Additionally, when the water is injected toward the endof the compression stroke in spark ignition engines (such as gasolineand natural gas engines) the moderating effect may reduce the potentialof detonation of the charge and engine knock.

FIG. 1 is an illustration depicting a waste heat recovery system. Aturbocharged engine system 100 is shown in FIG. 1. The engine 101 mayrun on a variety of fuels. For example, the engine 101 may run ondiesel, natural gas, or gasoline. The engine 101 may utilize spark orcompression ignition. Engine 101 comprises one or more cylinders 102.Cylinders 102 are supplied with intake air 103 from an intake manifold104. Cylinders 102 expel exhaust gasses 105 into exhaust manifold 106.Turbocharger 107 is positioned so that exhaust gasses 105 drive turbine108. Turbine 108 is connected to drive compressor 109. Compressor 109compresses intake air 103 to supply additional air flow to enginecylinders 102. In FIG. 1, after passing through compressor 109, intakeair 103 passes through an intercooler 110 to cool the air temperature ofintake air 103 and thereby making intake air 103 more dense. In someembodiments, EGR passage 111 connects exhaust manifold 106 to intakemanifold 104. An EGR cooler 112 and EGR valve 113 can control and cool aflow of exhaust gasses 105 that are mixed with intake air 103. Thismixture can reduce in-cylinder emissions.

In FIG. 1, waste-heat recovery system 120 comprises water tank 121.Water tank 121 can be filled by water supply 122. Water supply 122 canbe one or more of: (1) a plumbed water connection for a stationaryengine; (2) an amount of water that is refilled at certain intervals;and/or, (3), water condensed out of the exhaust gasses 105. Water tank121 supplies water 123 to a high pressure water pump 124. Water pump 124increases the pressure of the water 123 to a high level. This high levelis sufficiently high that the water 123 becomes supercritical as it islater heated. When it is heated sufficiently, the state of the water 123passes over the vapor dome.

The water pressure should be high enough to supply the discreteinjections into the cylinders in a short amount of time. Pressurizingthe water 123 to the point where it becomes supercritical when heatedalso has the advantage of avoiding multi-phase flow through the heatexchangers and injectors that would otherwise be present if the water123 was at a lower pressure and passed through the vapor dome uponheating. High pressure water pump 124 can be, for example, a dedicatedpump driven by the engine 101, or it can be integrated into an existingpump—such as a high pressure diesel fuel pump, if present.

Waste heat recovery system 120 can also be equipped with an optionalbypass 125. Bypass valve 126 (controlled by engine control unit 114) cancause the water 123 from the high pressure water pump 124 to be returnedback to the water tank 121 via bypass 125. This can be useful forperiods of operation such as engine warm-up, when there is not yetenough heat generated by the engine to sufficiently heat the water 123,and it is advantageous to effectively idle the waste-heat recoverysystem 120 thereby decreasing the power required by the high pressurewater pump 124.

Once the water 123 is pressurized, it travels through one or more heatexchangers 127 that heat the water with waste heat sources from theengine. These can include, but are not limited to, cooling water 115 ofengine 101, exhaust gasses 105 of engine 101, intercooler 110, and/orEGR cooler 112, if present. If exhaust gasses 105 of engine 101 are usedto heat water 123, the exhaust temperature may be lowered sufficientlyto condense water out of the exhaust to be at least a part of watersupply 122 of waste-heat recovery system 120. In an embodiment, water123 should be heated by exhaust gasses 105 post turbine 108, so thatenergy is not removed from exhaust gasses 105 before turbine 108,thereby decreasing the power of turbine 108 and negatively affecting theperformance of turbocharger 107. One exception may be for a high poweredgasoline engine. In a high powered gasoline engine, exhaust gasses 105should be cooled before entering turbine 108. This helps turbine 108from being damaged by excessively high temperatures.

In an embodiment, water 123 should be heated by cooling water 115 atwater 115's hottest point to both provide as much enthalpy as possibleto water 123, as well as to decrease a heat rejection requirement ofradiator 116. This hottest point is typically between engine 101 andradiator 116. In an embodiment, all parts containing heated water 123should be insulated to avoid losing enthalpy through heat transfer tothe ambient environment before the water 123 is injected. A desiredeffect of this heating process is to provide enough enthalpy to thewater 123 to make it supercritical, or a gas beyond the vapor dome, sothat when water 123 is injected into a cylinder 102, water 123 flashesto a vapor state in the cylinder 102.

At some engine operating conditions, such as idle or low load, there maynot be enough waste heat to heat the water 123 to the desired level. Inthese cases, in an embodiment, water 123 may be sprayed on a hot pistoninside engine cylinder 102 and thus evaporated inside cylinder 102. Inanother embodiment, water 123 may be heated by the pressurized charge inthe cylinder to similarly become a vapor. Otherwise, waste-heat recoverysystem 120 can be idled by opening bypass valve 126 and turning offdirect injectors 128.

Once water 123 has been heated to a high-enthalpy state, it is injecteddirectly into each cylinder 102. This can be done through a dedicateddirect injector 128. In an embodiment, if an injector for fuel, such asin a direct injection gas or diesel engine, is present, a parallelpassage in a fuel injector may be used to inject water 123simultaneously with the fuel. Engine control unit 114 operates theopening of the direct injectors 128 so that water 123 is injected at theend of the compression stroke. This avoids compression work on thepiston due to the additional mass of water 123 in cylinder 102. Withsufficient pressure, a desired quantity of water 123 can be injected ina short amount of time. This amount of time is similar to the durationnecessary for direct injection of diesel fuel in a direct injectiondiesel engine.

In this way, high-enthalpy water injection acts much like a steamengine: water 123 expands in the cylinder when it flashes to a lowerpressure through the injector 128. This steam engine type cycle happenssimultaneously to the regular combustion cycle, thereby enhancing thepower stroke. At the same time, the additional mass provided by water123 is at a substantially lower temperature than the combustionproducts, so water 123 absorbs heat from the combustion process. Thiscan additionally help the overall engine system by reducing NOxemissions, and reducing heat transfer to the cooling system through thecylinder 102.

In many engines, including diesel and natural gas engines, exhaust gasrecirculation, or EGR, is employed to achieve similar effects of coolingthe combustion gasses. Water is one of the major components ofrecirculated exhaust gas, so when water 123 is injected into cylinder102, water 123 will have a similar effect as the recirculated exhaustgas. Injecting water 123 into cylinder 102 can be used with or withoutEGR. The water 123 injection provides a benefit over EGR by reducing thepumping work of the engine 101. The pumping work of engine 101 isreduces because engine 101 does not need to compress the mass of water123 during the compression stroke because water 123 is injected largelyafter the compression stroke. For spark ignition engines, such asgasoline or natural gas engines, water 123 injections may also help toprevent knock in the cylinders by cooling and diluting the compressedcharge toward the end of the compression stroke.

FIG. 2 is a plot of a T-s diagram for water illustrating the physicalstates water takes as it is heated and injected into the cylinders. InFIG. 2, point 201 is the initial state of water 123 at atmosphericpressure and ambient temperature. Water 123 is then compressed by highpressure water pump 124 to state shown at point 202. Next, water 123travels up a constant pressure line 203 as water 123 is heated to asupercritical state at point 204. Finally, water 123 is injected intocylinder 102, where water 123 flashes into vapor state at point 205 bytraveling down constant enthalpy line 206.

FIG. 3 illustrates a direct injector that injects both fuel and steaminto the engine cylinders. In FIG. 3, direct injector 301 injects bothfuel and steam directly into cylinder 102. Injector 301 has separatedinternal passages: a fuel internal passage 302, and a water internalpassage 303. When the injector 301 opens, fuel is injected through fuelspray holes 304 into fuel plume 305, and heated water is injectedthrough steam spray holes 306 into steam plume 307.

FIG. 4 illustrates a direct injector 401 that is integrated into a glowplug 402. This provides a method of combining the direct injector 401into an existing engine component that is common in diesel engines sothat additional passages are not required in the engine cylinder head.The glow plug 402 provides heat to the engine cylinder 102 during enginestartup, when temperatures are cold to help enable combustion duringthis engine startup. The glow plug 402 has water passages 403 of thedirect injector 401 made internally to the glow plug 402 that feed steamspray holes 406 to inject water into the engine cylinder 102. In thisway, the direct injector 401 for the water and the glow plug 402 areintegrated into a single component.

FIG. 5 illustrates a direct injector 501 that is integrated into a sparkplug 502. This provides another method of combining the direct injector501 into an existing engine component that is used in spark ignitedengines to initiate combustion in the engine cylinder 102, avoiding theneed to have an additional passage in the engine cylinder head for thedirect injector 501. The spark plug has water passages 503 of the directinjector 501 made internally to the spark plug 502 that feed steam sprayholes 506 to inject water into the engine cylinder 102. In this way, thedirect injector 501 for the water and the spark plug 502 are integratedinto a single component.

It should be understood that the system described here forhigh-enthalpy, in-cylinder water injection can be used as an addition todiesel, gasoline, natural gas, or other internal combustion,turbocharged, piston engines to produce more engine work throughwaste-heat recovery, as well as moderating combustion to reduceemissions and heat transfer. The system provides benefits over existingmethods by utilizing an engine's pistons to extract energy through thewaste-heat process, instead of needing a separate, external device toextract this energy. The high cylinder pressures present duringcombustion also allow for a greater expansion of the waste-heat cyclethan can be utilized in most single stage, external system—such asturbines in an external Rankine cycle. This improves the efficiency ofthe waste-heat recovery system. In this way, high-enthalpy waterinjection is a pseudo-Rankine cycle, where the piston is used as theexpansion device to extract work. It also provides benefits over an EGRsystem for cooling the combustion products in that the moderating fluiddoes not need to be compressed by the cylinder during the compressionstroke (as is done in an EGR-only system), and improves breathing of theengine, as the additional mass of the recirculated gasses does not flowthrough the intake valves. The injected water may also be used tosuppress engine knock and detonation in spark ignition engines.

It should also be understood that a waste-heat recovery system to aturbocharged internal combustion piston engine that also can reduce NOxemissions is provided. This system can be added to spark or compressionignition engines. This system can be used by engines burning fuels thatinclude diesel, natural gas, and gasoline. A waste-heat recovery systeminvolves heating high pressure water with one or more waste heat sourcesof the engine including engine coolant, exhaust gas, intercooler, and/orEGR cooler if present. High enthalpy water is then distributed todirect, in-cylinder injectors in each of the engine cylinders where itis injected into the cylinder at a time corresponding to combustion ineach cylinder. The high-enthalpy water flashes into steam, providingadditional power to the engine, as well as acting as a moderating fluidto absorb combustion heat and reduce NOx emissions.

The foregoing description of the invention has been presented forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention to the precise form disclosed, andother modifications and variations may be possible in light of the aboveteachings. The embodiment was chosen and described in order to bestexplain the principles of the invention and its practical application tothereby enable others skilled in the art to best utilize the inventionin various embodiments and various modifications as are suited to theparticular use contemplated. It is intended that the appended claims beconstrued to include other alternative embodiments of the inventionexcept insofar as limited by the prior art.

What is claimed is:
 1. A component for a waste heat recovery system foran internal combustion engine, comprising: a glow plug to provide heatto an engine cylinder of said internal combustion engine during enginestartup; a plurality of water passages internal to and locatedcircumferentially around said glow plug to receive heated water suchthat said plurality of water passages and said glow plug are oneintegral component; and, a plurality of steam spray holes that interfacewith said plurality of water passages to produce a steam plumesurrounding said glow plug and internal to said engine cylinder whensaid plurality of water passages are supplied with said heated water,wherein said glow plug and said plurality of steam spray holes are tointerface to said engine cylinder via a single passage through an enginecylinder head of said internal combustion engine.
 2. The component ofclaim 1, wherein said heated water is injected into said engine cylinderat the end of a compression stroke of said at least one engine cylinder.3. The component of claim 1, wherein said heated water injected intosaid engine cylinder is pressurized and heated to a supercritical state.4. The component of claim 1, wherein said heated water is heated bycooling water and exhaust gasses of said internal combustion engine. 5.The component of claim 4, wherein said heated water is additionallyheated by an EGR cooler of said internal combustion engine.
 6. A methodof recovering waste heat for a turbocharged engine, comprising:providing an internal combustion engine with one or more cylinders, theinternal combustion engine to receive intake air and produce an exhaustgas flow of exhaust gasses; providing a turbocharger that extractsenergy from the exhaust gas flow and compresses intake air; providing awater reservoir; pressurizing water from said water reservoir to producepressurized water; heating said pressurized water with waste heat fromsaid internal combustion engine to produce supercritical water;providing one or more electronically controlled direct injectors thatinject said supercritical water into one or more cylinders of saidengine where said direct injectors are integrated into a waste heatrecovery component that provides heat to said one or more cylindersduring engine startup, said waste heat recovery component comprising: aglow plug; a plurality of water passages internal to and locatedcircumferentially around said glow plug to receive said supercriticalwater such that said plurality of water passages and said glow plug areone integral component; a plurality of steam spray holes that interfacewith said plurality of water passages to produce a steam plumesurrounding said glow plug and internal to a respective engine cylinderof said internal combustion engine when said plurality of water passagesare supplied with said supercritical water, wherein said glow plug andsaid plurality of steam spray holes interface to said respective enginecylinder via a single passage through an engine cylinder head of saidinternal combustion engine; and, injecting, using said waste heatrecovery component, said supercritical water into one or more cylindersof said internal combustion engine such that said water flashes into avapor thereby providing power to said one or more cylinders during apower stroke of said one or more cylinders.
 7. The method of claim 6,wherein water is condensed out of the exhaust gas flow and supplied tosaid water reservoir.
 8. The method of claim 6, wherein said pressurizedwater is heated by engine coolant and engine exhaust gasses downstreamof a turbine of said turbocharger.
 9. The method of claim 6, whereinsaid water is injected into said one or more cylinders at the end of acompression stroke of said one or more cylinders.
 10. The method ofclaim 6, wherein said water cools engine exhaust gasses prior to saidengine exhaust gasses entering said turbocharger.
 11. A turbochargedengine system, comprising: a turbocharger comprising a turbine and acompressor, the turbine to be powered by an exhaust gas flow of exhaustgasses of the engine system, the compressor to compress intake air; atank to hold water, the tank to receive water that was condensed out ofthe exhaust gas flow of the engine system; a pump to pressurize waterfrom said tank thereby producing pressurized water; one or more heatexchangers to, using heat produced by said engine system, heat saidpressurized water to a supercritical state thereby producingsupercritical water; and, an injector to inject said supercritical waterinto a cylinder of said engine system at a timing corresponding tocombustion in said cylinder where said injector is integrated into awaste heat recovery component, so that said water provides additionalpower to said cylinder during a power stroke of said cylinder, saidwaste-heat recovery component comprising: a glow plug; a plurality ofwater passages internal to and located circumferentially around saidglow plug to receive said supercritical water such that said pluralityof water passages and said glow plug are one integral component and, aplurality of steam spray holes that interface with said plurality ofwater passages to produce a steam plume surrounding said glow plug andinternal to a respective engine cylinder of said internal combustionengine when said plurality of water passages are supplied with saidsupercritical water, wherein said glow plug and said plurality of steamspray holes interface to said respective engine cylinder via a singlepassage through an engine cylinder head of said internal combustionengine.
 12. The engine system of claim 11, wherein a heat exchanger ofthe one or more heat exchangers is an intercooler.
 13. The engine systemof claim 11, wherein a first heat exchanger of the one or more heatexchangers is to utilize heat from engine coolant and exhaust gassesdownstream from said turbine to heat said pressurized water.
 14. Theengine system of claim 13, wherein a second heat exchanger of the one ormore heat exchangers is to heat said pressurized water using heat froman EGR cooler.
 15. The engine system of claim 11, further comprising: avalve to recirculate said water from said pump back to said tank toprevent injection of said water into said cylinder of said engine systemwhen heat produced by said engine system is insufficient to heat saidpressurized water.
 16. The engine system of claim 11, wherein said waterinjected into a cylinder of said engine system moderates combustion insaid cylinder thereby reducing NOx production.